A power converter to be mounted in a hybrid electric vehicle, an electric vehicle, and others is conventionally arranged to include a semiconductor device and an electric component for power conversion. Since the semiconductor device and others generate a large amount of heat during operation, the converter is provided with a cooling device to ensure heat dissipation characteristics. Herein, the cooling device is configured to contain heat dissipating fins in a cooling case and cause a coolant (a cooling medium) to flow in the cooling case to dissipate the heat generated in the semiconductor device and others into the coolant through the heat dissipating fins. This type of heat dissipating fins is disclosed in for example Patent Literature 1 listed below in which a plurality of heat dissipating fins are formed in parallel to a heat dissipating base plate.
Herein, as a technique to enhance a cooling performance of the heat dissipating fins (the cooling fin) as mentioned above, the present applicant has proposed a new “cooling fin and a method of manufacturing the cooling fin” and already filed a patent application thereof (e.g., Japanese patent application No. 2007-322831). This cooling fin integrally consists of a plurality of fin portions arranged in rows and a base portion that supports the fin portions. The shape of each fin portion in the coolant flowing direction is designed so that a root portion continuous to the base portion is straight and an edge portion is wavy or corrugated. To manufacture this cooling fin, firstly, the fin portions and the base portion are integrally formed by extruding into a comb-teeth and straight shape. Secondly, the edge portions of the fin portions made in straight shapes by extrusion are bent by a jig (pins) in a direction perpendicular to the extruding direction. This bending work is performed by inserting the jig (pins) into spaces or clearances between the fin portions. By this bending, the edge portions of the fin portions are corrugated along the coolant flowing direction.